Deoxycytidylic acid deaminase in Ehrlich ascites tumor cells.

verts dCMP to dUMP (13, 19), is present in mammalian tissues and manifests a high activity in such rapidly pro liferating tissues as embryonic tissue or tumors (3, 13, 15, 19). In tissues with a low mitotic index, the activity of the enzyme is quite low. Thus dCMP-deaminase activity is low in adult rat liver but increases when cell proliferation occurs in the organ, as for example after hepatectomy (14, 17) or during carcinogenesis (3, 5). These circumstances suggest that dCMP-deaminase plays an important role in the chemical mechanism of cell proliferation and that the intracellular activity of this enzyme is regulated co